Laboratory Zorn lab | Primary citation PMID 23125366 | |
 | ||
Description Xenbase: a Xenopus laevis and tropicalis bioinformatics resource. Data types
captured Literature, Nucleotide Sequence, RNA sequence, Protein sequence, Structure, Genomics, Morpholinos, Metabolic and Signaling Pathways, Human and other Vertebrate Genomes, Human Genes and Diseases, Microarray Data and other Gene Expression, Proteomics Resources, Other Molecular Biology, Organelle Organisms Xenopus laevis and Xenopus tropicalis Research center Cincinnati Children's Hospital | ||
Xenbase is a Model Organism Database (MOD), providing informatics resources, as well as genomic and biological data on Xenopus frogs. Xenbase has been available since 1999, and covers both X. laevis and X. tropicalis Xenopus varieties. As of 2013 all of its services are running on virtual machines in a private cloud environment, making it one of the first MODs to do so. Other than hosting genomics data and tools, Xenbase supports the Xenopus research community though profiles for researchers and laboratories, job and events postings, and a number of discussion forums at http://forums.xenbase.org.
Contents
Xenbase's Software and Hardware Platform
Xenbase runs in a cloud environment. Its virtual machines are running in a VMware vSphere environment on two servers, with automatic load balancing and fault tolerance. Xenbase software uses Java, JSP, JavaScript, AJAX, XML, and CSS. It also uses IBM's WebSphere Application Server and the IBM DB2 database.
Xenopus as a model organism
The Xenopus model organism is responsible for large amounts of new knowledge on embryonic development and cell biology. Xenopus has a number of unique experimental advantages as a vertebrate model. Paramount among these is the robustness of early embryos and their amenability to microinjection and microsurgery. This makes them a particularly attractive system for testing the ectopic activity of gene products and loss-of-function experiments using antagonizing reagents such as morpholinos, dominant-negatives and neomorphic proteins. Morpholinos are synthetic oligonucleotides that can be used to inhibit nuclear RNA splicing or mRNA translation and are the common gene inhibition reagent in Xenopus as neither siRNA or miRNA have yet been shown to reproducibly function in frog embryos. Xenopus embryos develop very quickly and form a full set of differentiated tissues within days of fertilization, allowing rapid analysis of the effects of manipulating embryonic gene expression. The large size of embryos and amenability to microinjection also makes them extremely well suited to microarray approaches. Furthermore, these same characteristics make Xenopus, one of the few vertebrate model organisms suited for chemical screens. Xenbase provides a large database of images illustrating the full genome, movies detailing embryogenesis, and multiple online tools useful for designing and conducting experiments using Xenopus.
Xenbase Contents and Tools
Xenbase provides many tools useful for both professional research as well as academic learning. Highlighted below are a few of the tools, along with a brief description. For full details on provided tools, users are referred to Xenbase's publications.
2012 Nobel prize in Xenopus research
The Nobel Prize for Medicine or Physiology was awarded to John B. Gurdon and Shinya Yamanaka on October 8, 2012. for nuclear reprogramming in Xenopus.
Importance: Gurdon's experiments challenged the dogma of the time which suggested that the nucleus of a differentiated cell is committed to their fate (Example: a liver cell nucleus remains a liver cell nucleus and cannot return to an undifferentiated state).
Specifically, John Gurdon's experiments showed that a mature or differentiated cell nucleus can be returned to its immature undifferentiated form; this is the first instance of cloning of a vertebrate animal.
Experiment: Gurdon used a technique known as nuclear transfer to replace the killed-off nucleus of a frog (Xenopus) egg with a nucleus from a mature cell (intestinal epithelial). The tadpoles resulting from these eggs did not survive long (past the gastrulation stage), however, further transformation of the nuclei from these Xenopus eggs to a second set of Xenopus eggs resulted in fully developed tadpoles. This process (transfer of nuclei from cloned cells) is referred to as serial transplantation.
Xenopus Research Utilizing Xenbase Tools
To provide examples of how Xenbase could be used to facilitate academic research, two research articles are briefly described below.
This paper uses Xenbase resources to create and characterize mutations in Xenopus tropicalis. Goda et al., performed a large scale forward genetics screen on X. tropicalis embryos to identify novel mutations (2006). Defects were noted and put into 10 different categories as follows: eye, ear, neural crest/pigment, dwarf, axial, gut, cardiovascular, head, cardiovascular plus motility, and circulation. Further studies were performed on the whitehart mutant "wha" which does not have normal circulating blood. The Xenopus Molecular Marker Resource page was used to design a microarray experiment which compared wild type (normal circulation) and "wha" mutant X. tropicalis. Analysis of microarray data revealed that 216 genes had significant changes in expression, with genes involved in hemoglobin and heme biosynthesis being the most affected, consistent with the observation that "wha" may have a role in hematopoiesis.
The 2013 paper by Suzuki et al. describes the use of a relatively new gene knockdown technique in X. laevis. Traditionally, antisense morpholino oligonucleotides have been the method of choice to study the effects of transient gene knockdown in Xenopus.
In comparison to morpholinos which disrupt gene expression by inhibiting translational machinery TALENs disrupt gene expression by binding to DNA and introducing double stranded breaks. Xenbase was utilized to obtain publicly available sequences for tyrosinase (tyr) and pax6, needed for TALEN design. Knockdown of both pax6 and tyr was highly efficient using TALENs, suggesting that gene disruption using TALENs may be an alternative or better method to use in comparison to antisense morpholino's.